INS Alignment procedure (draft)

Here are the INS alignment procedures available for the AV-8B NA. As stated in the title, this is a draft document and some steps can be modified/deleted.

AV-8B N/A INS Alignment Procedures:

1. There are four alignment modes:

2. There are three alignment sub-modes:

3. The main alignment sequence is the same for all modes & sub-modes:

How to do an INS alignment (all modes):

1. Make sure that the INS mode selector knob is in the OFF position.

2. Select EHSD on the MPCD (Left or Right).

3. Select DATA on the MPCD

4. Select AC on the MPCD.

5. Enter AC present position (lat/lon).

6. Enter local magnetic variation (MVAR) if the value shown is 0

7. Place the INS mode selector knob in the selected alignment mode: SEA, GND, IFA or GYRO. The alignment process will start immediately IF THE REQUIRED INFORMATION IS PRESENT.

8. When alignment is finished, place the INS mode selector knob either in NAV or IFA (for GPS coupled navigation).

SEA Alignment:

SEA alignment can only be performed aboard a carrier.

SINS

The main SEA alignment mode is the Ship Inertial Navigation System (SINS) mode. In this mode, the aircraft connects to the ship’s INS and use it to achieve INS precision.

SINS and IFA are the only modes in which aircraft present position is not required to be entered by the pilot.

The aircraft connects itself to the ship’s INS via deck cable or by using either COM1 or COM2 radios. The ODU displays the following:

MANUAL SEA ALIGNMENT

MANUAL SEA alignment is a sub-mode of the SEA alignment and used when SINS is not available. MANUAL and SINS are mutually exclusive. Selecting MANUAL will deselect and disable SINS. To return to SINS, the INS mode selector knob must be changed to another mode and then back to SEA.

In MANUAL SEA alignment the following data is required:

1. Aircraft present position.

2. Ship’s heading and speed.

3. Aircraft’s TRUE heading.

4. Local magnetic variation if it does not exist in the system.

To select MANUAL:

1. Click on the MAN option pushbutton in the EHSD page.

2. MAN option will be boxed

3. SINS option will be unboxed and removed from the screen.

4. The UFC/ODU will be placed in MANUAL SEA mode for data entry.

5. Input the required data so the process can start.

GND Alignment

GND (Ground) alignment is performed with the aircraft on land. If the parking brake is released, the alignment process enter into hold mode. If the aircraft moves too far from its present position the INS caution light will turn on indicating an invalid INS present position and entire process must be restarted.

STORED HEADING ALIGNMENT

The Stored Head alignment’s purpose is to reduce total align time by bypassing the Wide Angle Grycompass step.

This procedure can be performed when:

1. The aircraft is parked and parking brake is set.

2. A complete INS ground alignment has been previously performed.

3. The aircraft has not moved since the alignment.

4. NAV has not been selected in the INS mode selector knob.

Stored Heading alignment availability is indicated by the presence of the SHDG pushbutton on the upper left corner of the ground align display.

To select Stored Heading alignment, click on the SHDG pushbutton.

The SHDG pushbutton will be removed when the alignment process enters into Wide Angle Gyrocompass, at which point the stored heading will be deleted from the system.

In-Flight-Alignment (IFA)

IFA uses the GPS to continuously update the INS.

If IFA is selected without an aligned INS, the GPS data will be used to align the INS. This is the only mode that allows INS alignment while the aircraft is moving. Aircraft present position is not required to be entered by the pilot since it is provided by the GPS.

The alignment process will enter in hold mode when:

1. Aircraft roll exceeds 30 degrees, or

2. Aircraft pitch is greater than 15 or less than -5 degrees.

If the aircraft is moving, INS alignment can take as much as 10 minutes.

The INS will automatically enter into coupled navigation mode as soon as the IFA alignment process ends.

When the INS is in IFA mode, INS position update is not required.

GYRO Alignment.

This mode provides a quick 33 seconds alignment process. If used aboard a ship it can take 45 seconds.

Present position data is not available in GYRO.

GYRO mode is the least accurate navigation mode and full inertial navigation mode cannot be achieved in flight after using GYRO, even if the INS mode selector is changed to NAV. To obtain full inertial navigation an IFA alignment must be performed (10 minutes process).

GYRO mode is susceptible to precession errors and large errors (greater than 5 degrees) in both heading and attitude are possible.

ATTENTION

The alignment process will not start if the required information is not present:

1. Valid aircraft Present Position (Not required for SEA SINS and IFA).

2. Local magnetic variation (Not required for SEA SINS and IFA).

3. CV's heading and speed (SEA Manual mode only).

4. Aircraft True Heading (SEA Manual model only).

Taking off with the INS in the OFF position can result in unit damage due to acceleration forces.

Sounds great! Thanks for that

Will there be a Option to skip alignment like In the Mirage?

Sounds great! Thanks for that

 

Will there be a Option to skip alignment like In the Mirage?

Yes there will be a Pre-Aligned INS option.

Is this coming in the next update?

Nice! So, will the INS mode selector knob get working CW/CCW key binds? If not now, at any point in the future?

Nice! So, will the INS mode selector knob get working CW/CCW key binds? If not now, at any point in the future?

The CW/CCW key binds are there right now.

Is this coming in the next update?

Depends. This is the main problem with complex aircrafts. We must be sure that our procedures work as stated and also this requires some modifications to the INS to account for degraded functionality.

The CW/CCW key binds are there right now.

I know, that's why I said working ;) For me these have no effect or at least the knob is not animated.

Will drift be modelled and will the drift factor vary depending on INS precision?

Will drift be modelled and will the drift factor vary depending on INS precision?

Yes, but in this aircraft it is a moot question. If you set the mode to IFA, the INS and GPS are coupled and no drift error will occur.

IFA is the default mode to be used in the AV-8B N/A and Plus.

Alright, thanks.

Glad to hear it's coming soon. Thanks.

Fantastic.

Yes, but in this aircraft it is a moot question. If you set the mode to IFA, the INS and GPS are coupled and no drift error will occur.

 

 

IFA is the default mode to be used in the AV-8B N/A and Plus.

So it’s common to start the AV8B in IFA mode without pre alignment on the ground? That’s great for operation timing

So it’s common to start the AV8B in IFA mode without pre alignment on the ground? That’s great for operation timing

No. You align the INS normally. After the INS is aligned, you set the operational mode to IFA, so the GPS and INS couple and drift errors are eliminated.

Pure inertial navigation (NAV) is considered degraded mode.

Do we need to enter MAGVAR prior to alignment? Every INS I've used could figure out True North by detecting the Earth's rotation and taking a 90 degree offset. MAGVAR in every INS I have used was to offset the gyro-stabilized HSI to magnetic headings, and you only needed to do that if the onboard database was obsolete.

Will be possible to do the process with the APU and then start the engine for taxi/takeoff or you need the engine on during the entire process?

Will be possible to do the process with the APU and then start the engine for taxi/takeoff or you need the engine on during the entire process?

You can also use ground power.

Do we need to enter MAGVAR prior to alignment? Every INS I've used could figure out True North by detecting the Earth's rotation and taking a 90 degree offset. MAGVAR in every INS I have used was to offset the gyro-stabilized HSI to magnetic headings, and you only needed to do that if the onboard database was obsolete.

Only if MAGVAR is not saved in the unit. Otherwise, yes. You must enter it.

This will happen when:

a. At random from a cold and dark start (50/50 chance).

b. Always after having to repair the INS unit (it is a new INS blackbox).

Not required for a Carrier SINS or IFA, since the data is fed into the unit from external sources.

So, in a Cold and Dark start you will be required to check MAGVAR if value is 0 then you must enter it.

Will be possible to do the process with the APU and then start the engine for taxi/takeoff or you need the engine on during the entire process?

You need AC power for the INS so you can use APU, Engine or Ground Power.

4 to 10 minutes? I'm gonna need popcorn on my side

I don’t want to sound like a killjoy but would like your modules to align with ED policy and remove the already aligned option. It offers an unfair advantage in turnaround time on mp and is unrealistic. People can have the plane start hot and already aligned if the wait is too long for them.

I don’t want to sound like a killjoy but would like your modules to align with ED policy and remove the already aligned option. It offers an unfair advantage in turnaround time on mp and is unrealistic. People can have the plane start hot and already aligned if the wait is too long for them.

I don’t want to sound like a killjoy but would like your modules to align with ED policy and remove the already aligned option. It offers an unfair advantage in turnaround time on mp and is unrealistic. People can have the plane start hot and already aligned if the wait is too long for them.

The whole DCS environment is unfair and unbalanced, by design, as we get mostly planes that are pretty different. That doesn't mean it isn't fun.

We have Arcade mode, F10 view, padlock and dozens of other "unfair" options to choose from.

It might be an option to ask for a mission editor checkbox, but the option itself is there, for a very good reason.

I don’t want to sound like a killjoy but would like your modules to align with ED policy and remove the already aligned option. It offers an unfair advantage in turnaround time on mp and is unrealistic. People can have the plane start hot and already aligned if the wait is too long for them.

+1

While DCS is definitely not a tournament or esports game or anything similar, it is a flight sim and as such should stick to realism. Unbalanced gameplay in DCS should be a result of realism and not because some people prefer to use arcade mode or other unrealistic cheats. Really not happy with RAZBAMs policy on this :(